A trunking communication system is a dedicated wireless communication system, which is developed for meeting a commanding and scheduling requirement of a user in the industry and oriented to a specific industrial application. A large number of wireless users share a small number of wireless channels in the system; the system is mainly applied for commanding and scheduling, and is a multipurpose and high-performance wireless communication system. The trunking communication system has a broad application market in the fields of government departments, public security, emergency communication, power, civil aviation, petrochemical industry, military and the like.
A trunking communication system experiences a development history similar to a cellular mobile communication system. A first-generation trunking system is an analogue trunking communication system, which mainly supports voice communication. The analogue trunking communication system earliest introduced into China is an Actionet system of the Nokia corporation, and the system adopts MPT-1327 signalling applied to a 450 MHz frequency band. Then, F.A.S.T of Japan and Smartnet of Motorola corporation of the United States are introduced into China, and the market share occupied by them in the trunking market in China is more than 80 percent for a long term.
A second-generation trunking system is a narrowband digital trunking communication system, rising in the 1990s, and is started to be deployed in China in about 2004, which is a trunking communication system most widely applied in China at present. The digital trunking communication system supports voice and low-speed data (at most 28.8 kbps) communication, and representative systems include a Terrestrial Trunked Radio (TETRA) system defined by the European Telecommunications Standards Institute (ETSI), an Integrated Digital Enhanced Networks (iDEN) system of the Motorola corporation of the United States, a Global Open Trunking Architecture (GoTa) system developed by the ZTE Corporation on the basis of Code Division Multiple Access 1X (CDMA1X), and a GT800 system developed by the Huawei Technologies Co., Ltd. on the basis of Global System for Mobile Communications (GSM). In recent two to three years in China, Terrestrial Trunked Radio (TETRA) networks grow fastest, and the number of the TETRA networks is about 2/3 of digital trunking communication networks constructed in the whole country.
A characteristic differentiating a trunking system from a public system is that the trunking system is required to have an efficient commanding and scheduling characteristic and a network is required to have high reliability and security.
Call control: a service bearer is established, maintained and released between a calling user and a called user according to a service request of a user.
Authentication and certification: authentication and certification functions are supported, and the authentication function includes authentication performed by a network side for a terminal and two-way authentication performed by the network side for the terminal and performed by the terminal for the network side.
Fail soft: when a link between a network side and an eNB or between network elements inside the network side fails, the eNB may provide limited trunking service for user terminals within its coverage.
Network interconnection and intercommunication function: intercommunication with a Public Switched Telephone Network (PSTN), a public mobile communication system (a GSM or CDMA, Time Division-Long Term Evolution (TD-LTE) and the like), an Internet Protocol (IP) telephone, a trunking communication system of another model and the like may be implemented. In 3rd Generation Partnership Project (3 GPP) LTE, trunking communication is called as a Group Communication Service Enabler (GCSE). FIG. 1 is a system structure of an LTE GCSE.
For effectively utilizing a mobile network resource, the 3GPP proposes a Multimedia Broadcast Multicast Service (MBMS), which is a technology for transmitting data from a data source to multiple target mobile terminals, and the MBMS implements sharing of a network (including a core network and an access network) resource and increases a utilization rate of the network resource (particularly an air interface resource). The MBMS defined by the 3GPP may not only implement to multicast and broadcast pure-text low-rate message but also implement to broadcast and multicast high-speed multimedia service and the MBMS provides various video, audio and multimedia services, which undoubtedly follows a development trend of mobile data in the future and provides broader service prospect for development of 3rd or 4th-Generation (3 or 4G).
Characteristics of the MBMS are large service data volume, long receiving duration of a mobile terminal and constant average data rate. The aforementioned characteristics determine that both scheduling and control signalling configuration of the MBMS are semi-static, that is, scheduling information and control signalling information of the MBMS are kept unchanged “for a long time”, and the information is periodically sent through an MBMS Control Channel (MCCH), and is collectively referred to as MCCH information. Multiple MCCHs may exist in an Evolved MBMS (eMBMS) system, each MCCH corresponds to a different Signal Frequency Network (MBSFN) area, and only control information of an MBMS sent by a corresponding MBSFN area is borne on the MCCH. FIG. 2 is a structure diagram of an MBMS in LTE.
At present, the industry is discussing the probability to realize trunking communication by adopting an MBMS technology. For specific trunking User Equipment (UE), a required trunking service may be received in any one of the following two manners: multicast and unicast, wherein the multicast manner is that the trunking service is borne and received through the MBMS, and at this moment, the UE is required to have an MBMS receiving capability.
In a researching and practicing process in the related technology, it is found that the related technology has the following problems: a Group Communication Service (GCS) Application Server (AS) sends a congestion or overload detection request to a Multicell/Multicast Coordination Entity (MCE); the MCE which receives the request sends a request to all eNBs in an MBSFN area; and the eNB which detects congestion or overload reports information to the GCS AS through the MCE. Since congestion or overload occurs in all the eNBs in the MBSFN area, all the eNBs in the MBSFN area report the same information to the MCE, which obviously wastes an M2 interface resource and reduces work efficiency.